Only four years after the discovery of Neanderthal, three grand questions were said to be under discussion in ‘the higher branches of ethnology’. In a lecture presented at the Mechanics' Institution, Liverpool, the nineteenth-century polymath R. G. Latham (1851: 49) defined these as:

1. The unity or non-unity of the species.

2. Its antiquity.

3. Its geographical origin.

Other writers today have pointed back to this text too, and it still guides research and speculation in the field of human origins.

From findings in genetics we now know that all living branches of humanity are descended from a small population of southern or eastern Africans. Even arguments for the contribution of non-African genetic material to modern humanity remain sparse and a minority view (for a brief review of the evidence, see Stoneking 2006). Although much of the globe had previously been colonized by Homo erectus and later species, all humanity in Asia, Australia, Europe and the Americas came much later, from eastern Africa. The population bottleneck of early H. sapiens sapiens may have numbered as few as 2,000 (Wells 2007: 140). Because of the effects of the Toba volcanic explosion around 74,000 BP (or sometime between 77,000 and 69,000 BP), we can date the start of the main H. sapiens sapiens human global migrations: perhaps 60,000 BP, but not much earlier. Supporters of the Toba theory (e.g., Ambrose 1998) hold that such arguments account for data in many fields, although it is also possible that there were one or more migrations before Toba and that this produced surviving populations that mixed with the migrants of 60,000 years ago (see Oppenheimer 2004: 166–84).